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New 6mm Advanced Rifle Cartridge

She's a shooter. Sub-MOA with factory loads; took it out to 1,025 yards today. The 6 ARC is growing on me ... a lot.

IMG_1380.jpeg
 
Finally got the X-Caliber 13", mlgs lightweight barrel that I ordered back in March in. Going to try a BFK Mod 0 thermal fit upper and reuse a 12.7" Aero handguard I have on this one. Waiting for Rexus Ultra bolts to come back in stock in the next few weeks and should be in business.

PXL_20250715_035646026.jpg
 
get a fix.

Handiest bolt gun around

Indeed - MiniFix in 6ARC with a Proof Carbon barrel is the handiest bolt gun in my collection. I can strip it down to just the 3-20x and lug it up and down the mountains like it's no big deal at all.

Or I can load it up with some craziness...
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Oh and I'll add, I've now gone through a number of different barrel lengths in semi-autos - from 26" to 20" to 16" to 12". I really think with anything longer than 16" you rapidly hit a point of diminishing returns with this cartridge. Granted, I'm not using commercial ammo, so maybe that'll run better, but my own 103 ELD-X / 105 Hybrid / 109 LRHT loads don't see a significant boost in velocity past 16", at least not the 25fps / inch expectation you see with other rifle/cartridge combos. I just started shooting the 12" and it's crazy how a shorty can essentially perform like an old school full size Mk12.
 
Indeed - MiniFix in 6ARC with a Proof Carbon barrel is the handiest bolt gun in my collection. I can strip it down to just the 3-20x and lug it up and down the mountains like it's no big deal at all.

Or I can load it up with some craziness...
View attachment 8731851
Damn, save some pussy for the rest of us!
 
Oh and I'll add, I've now gone through a number of different barrel lengths in semi-autos - from 26" to 20" to 16" to 12". I really think with anything longer than 16" you rapidly hit a point of diminishing returns with this cartridge. Granted, I'm not using commercial ammo, so maybe that'll run better, but my own 103 ELD-X / 105 Hybrid / 109 LRHT loads don't see a significant boost in velocity past 16", at least not the 25fps / inch expectation you see with other rifle/cartridge combos. I just started shooting the 12" and it's crazy how a shorty can essentially perform like an old school full size Mk12.
And here I have a 22” ar barrel on the shelf for a gas gun comp build when the m lol Vltor vis gets released
 
Oh and I'll add, I've now gone through a number of different barrel lengths in semi-autos - from 26" to 20" to 16" to 12". I really think with anything longer than 16" you rapidly hit a point of diminishing returns with this cartridge. Granted, I'm not using commercial ammo, so maybe that'll run better, but my own 103 ELD-X / 105 Hybrid / 109 LRHT loads don't see a significant boost in velocity past 16", at least not the 25fps / inch expectation you see with other rifle/cartridge combos. I just started shooting the 12" and it's crazy how a shorty can essentially perform like an old school full size Mk12.

So what were the velocities with the same loads and different barrel lengths?
 
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I have read that 18 was optimal but that’s been a couple years and maybe factory only ammo, although I’m not entirely sure why hand loading would make a shorter barrel have less delta than factory ammo 🤷‍♂️
 
It has settled to a 2465 average with factory 108's.
Wow. Yeah, pretty similar.
I shot some last fall just because I had a couple boxes laying around. Here’s what I got.
Hornady 108 ELDM Factory
2504, 2506, 2480, 2472, 2445
2505, 2492, 2488, 2480, 2463
2498, 2517, 2511, 2513, 2510
2479, 2511, 2487, 2508, 2494
SD 18.5 ES 72 2”
 
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I love my 14.5", it didn't give up much over the 18" I ran prior. Now I need to decide on a proper 22ARC barrel for the next build.
I think for 22 ARC 18" is it. 2850 with 88gr eld m is a commonplace with factory ammo. I guess you could do 16" and run 2700 or so. I'm sure if you're loading that's different but it just doesn't seem to hold velocity as well as the 6 ARC when chopping the barrel. I know I'll be going 16" for my 6 ARC
 
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I think for 22 ARC 18" is it. 2850 with 88gr eld m is a commonplace with factory ammo. I guess you could do 16" and run 2700 or so. I'm sure if you're loading that's different but it just doesn't seem to hold velocity as well as the 6 ARC when chopping the barrel. I know I'll be going 16" for my 6 ARC

I'd like to keep it no longer than 16" for the 22ARC. I want that build strictly for varmints. Something I can throw the thermal on and have little to no drop out to 300. I haven't started exploring the best factory loads just yet. Sadly, some have said the initial Proof barrels had issues.
 
I'd like to keep it no longer than 16" for the 22ARC. I want that build strictly for varmints. Something I can throw the thermal on and have little to no drop out to 300. I haven't started exploring the best factory loads just yet. Sadly, some have said the initial Proof barrels had issues.
In that case 62gr eld vt should still be plenty fast in a 16” i did hear about the proofs but you can always go craddock RTR
 
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